Oxidation resistance of powder metallurgy Ti-45Al-10Nb alloy at high temperature

TiAl alloy with high Nb content, nominally Ti-45Al-10Nb, was prepared by powder metallurgy, and the oxidation resistance at 850, 900, and 950 degrees C was investigated. The high-temperature oxidation-resistance mechanism and oxidation dynamics were discussed following the oxide skin morphology and microstructural evolution analysis. The oxide skin structures were similar for 850 and 900 degrees C, with TiO2+Al2O3 mixture covering TiO2 with dispersed Nb2O5. At 950 degrees C, the oxide skin was divided into four sublayers, from the outside to the parent metal: loose TiO2+Al2O3, dense Al2O3, dense TiO2+Nb2O5, and TiO2 matrix with dispersed Nb2O5. The Nb layer suppressed the outward diffusion of Ti atoms, hindering the growth of TiO2, and simultaneously promote the formation of a continuous Al2O3 protective layer, providing the alloy with long-term high-temperature oxidation resistance.

Automated summary

In this study, a TiAl alloy with high Nb content was prepared through powder metallurgy, and its oxidation resistance at different temperatures was investigated. The mechanism and dynamics of high-temperature oxidation resistance were discussed based on the morphology and microstructure evolution of the oxide skin.